This invention relates polyurethanes and to compositions of relatively high equivalent weight active hydrogen compounds and alkylene glycols, said compositions containing materials that make the compositions useful in preparing polyurethanes.
In making polyurethanes mixtures of a relatively high equivalent weight active hydrogen compound and a relatively low equivalent weight chain extender compound are reacted with a polyisocyanate. Using alkylene glycols as chain extenders often produces advantageous properties in resulting polyurethanes.
Alkylene glycol chain extenders are, however, often incompatible with relatively high equivalent weight active hydrogen compounds in amounts used to make polyurethane polymers. Therefore, the relatively high equivalent weight active hydrogen compound is often blended with the alkylene glycol just prior to use. Alternatively, an additional component which compatibilizes the alkylene glycol with the relatively high equivalent weight active hydrogen compound may be used. For instance, the use of urea and certain substituted ureas as compatibilizing agents is taught in U.S. Pat. Nos. 4,485,031 and 4,485,032.
Use of compatibilizing agents is generally preferred because such use allows shipping and storage of blends of relatively high equivalent weight active hydrogen compounds and chain extenders. In many instances, the blends also contain other materials used in preparing polyurethanes, such as catalysts and certain additives. The reactivity of blends containing relatively high equivalent weight active hydrogen compounds, alkylene glycol chain extenders, compatibilizers having amine or urea functional groups and tin-containing catalysts such as certain dialkyl tin dicarboxylates often diminishes during storage.
Some blends of polyether polyols and alkylene glycols compatibilized with ureas taught in U.S. Pat. No. 4,485,032 show sufficient reactivity with isocyanates to form polyurethanes in the absence of tin carboxylate catalysts, but require 60 second demold times which exceeds the preferable demold times in automatic RIM processes.
Accordingly, it would be desirable to provide a compatibilized blend of relatively high equivalent weight active hydrogen compounds and glycol which blend contains materials catalytic for polyurethane formation and exhibits relatively stable reactivity over time. It would also be desirable for the blend to have sufficient catalytic activity to produce polyurethanes which can be demolded in less than about 60 seconds. Preferably, the blend would also provide mold release properties for a polyurethane produced from the blend.